Surfaces of thermoplastic sheets and structures modified with photocatalytic materials

Abstract

Thermoplastic surface modification is achieved with photocatalysts, such as titanium dioxide, tungsten oxide and mixtures thereof. A uniform coating of a powdered photocatalyst is applied to a thermoplastic surface that is wetted with an organic solvent. The coating is in a range between approximately 1.5 mg/cm 2 to approximately 2.5 mg/cm 2 . After the uniform coating of photocatalyst is dried, the thermoplastic surface is heated to a temperature above its softening temperature, usually in a range between approximately 80° C. to approximately 130° C.; then, a mild pressure is applied to imbed the photocatalyst into the surface of the thermoplastic sheet. The method of modification is inexpensive, long-lasting and non-detrimental to the thermoplastic surface. A surface is provided with improved aesthetic appearance, extended lifetime and sustained protection from undesirable growth of nuisance organisms, such as algae, fungus, bacteria, mold, mildew and the like.

1. A thermoplastic sheet selected from the group consisting of:
 thermoplastic polyolefin (TPO) and polyvinyl chloride (PVC) modified with an imbedded photocatalyst on one wetted surface side a thermoplastic surface comprising TiO.sub.n1, wherein 0<n1<2, and the imbedded photocatalyst comprising wetted particles having sizes of 0.1 to 0.25 mm, the wetted particles having a uniform coating that has been loaded in a range between approximately 1.5 mg/cm 2  to approximately 2.5 mg/cm 2  on the wetted one side of the thermoplastic surface to form a modified thermoplastic Sheet, the modified thermoplastic sheet having a modified surface that is resistant to the growth of nuisance organisms including damaging algae, fungus, bacteria, mold and mildew. 
 
     
     
       2. The thermoplastic sheet of  claim 1 , wherein the uniform coating on the modified thermoplastic sheet is loaded at a density of approximately 2.0 mg/cm 2  on the thermoplastic surface. 
     
     
       3. The thermoplastic sheet of  claim 1 , wherein the wetted particles include solvent wetted particles. 
     
     
       4. A structural material having a surface that is resistant to the growth of nuisance organisms, comprising:
 a) a thermoplastic sheet with a softening point above approximately 50° C. selected from a group consisting of thermoplastic polyolefin (TPO) and polyvinyl chloride (PVC), thermoplastic sheet having one wetted surface side; and 
 b) a uniform coating of a photocatalyst, in active form heat imbedded into a surface of the thermoplastic sheet, the photocatalyst selected from the group consisting of a wetted mixture of TiO.sub.n1, wherein 0<n1<2, and the photocatalyst wetted mixture having particle sizes of 0.1 to 0.25 mm to form the uniform coating, the uniform coating loaded in a range between approximately 1.5 mg/cm 2  to approximately 2.5 mg/cm 2  on the wetted one side of the thermoplastic surface. 
 
     
     
       5. The structural material of  claim 4 , wherein the thermoplastic sheet has a softening point in a range between approximately 80° C. to approximately 140° C. 
     
     
       6. The structural material of  claim 4 , wherein the uniform coating is loaded at a density of approximately 2.0 mg/cm 2  on the thermoplastic surface. 
     
     
       7. The structural material of  claim 4 , wherein the wetted photocatalyst mixture is a solvent wetted photocatalyst mixture. 
     
     
       8. The structural material of  claim 4 , wherein the wetted surface of the thermoplastic sheet is a solvent wetted surface. 
     
     
       9. A thermoplastic sheet, comprising:
 thermoplastic polyolefin (TPO) and polyvinyl chloride (PVC) modified with an imbedded photocatalyst on one wetted surface side a thermoplastic surface comprising TiO.sub.n1, wherein 0<n1<2, the imbedded photocatalyst comprising wetted particles having sizes of 0.1 to 0.25 mm, the wetted particles having a uniform coating that has been loaded in a range between approximately 1.5 mg/cm 2  to approximately 2.5 mg/cm 2  on the wetted one side of the thermoplastic surface to form a modified thermoplastic sheet, the modified thermoplastic sheet having a modified surface that is resistant to the growth of nuisance organisms including damaging algae, fungus, bacteria, mold and mildew.